What is the Sharīʿah's ruling regarding a woman who is given the choice between submitting to an abusive husband, returning the dowry, or being considered defiant (nashiz) and forfeiting her rights?

What the Sharia requires is that if the husband harms his wife and is not deterred except by separation, then separation between them becomes obligatory without any compensation from her. This is based on the Prophet's (peace be upon him) saying: "There should be no harm nor reciprocating harm," and Allah’s Almighty saying: "Retention with honor or dismissal with kindness." So, he who falls short in his wife's rights and harms her with insults or beatings, if he keeps her in this state, he is not retaining her with honor, and if he dismisses her for compensation, he is not dismissing her with kindness. The obligation is to remove the harm from the wife caused by this oppressor. Imam Malik said in Al-Muwatta: If a husband harms his wife and restricts her, and it is known that he is unjust to her, the divorce proceeds, and her money is returned to her. This is the correct ruling if it is proven that the wife is harmed by remaining in her husband's marital bond and the harm cannot be removed except by separating them.